I changed my shop name last October. It's an easy process but be absolutely sure what you want because you can only change it once.
When you change it the little house thing next to your shop name in posts and stuff will show a tiny arrow pointing to another house thing. When someone hovers their mouse over it it'll say that you changed your shop name from PrettyTurkishThings. That won't stay there forever but it's a nice feature so people on the forums recognize you.
Changing your name does not affect your shop stats and your followers will see you with your new shop name. Any links you have posted with your old shop name will automatically reroute to the new shop name.
I don't think there's a rule that you have to disclose your old shop name but it wouldn't hurt to put something in your shop announcement. I put the info at the very bottom of my shop announcement so it's there, but it's not the main focus.
You absolutely need to disclose that your aunt is part of your shop. You have what's called a collective shop. If you look under Etsy Do's and Don'ts, Multiple People Using a Single Account, it sounds like yours would fall under the "Shop Management Help." In your shop profile you can list both your names and explain the role each of you has in the shop.
http://www.etsy.com/help/article/483#membership_multiple_people